This invention relates to a charger and, more particularly, to a battery charger for charging a battery pack for use in various electric machines, equipments, tools and so on.
For storage battery used in rechargeable battery-powered machines, equipments, tools and so on, a nickel-cadmium or a nickel-hydrogen battery has been widely used recently. Upon recharging such kind of batteries, however, there has occurred often a trouble such that, in the event where the battery is overcharged due to any fault of the charger or when an actuating pressure of safety valve of the battery is lowered in the last period of inherent life of the battery, the battery being charged generates hydrogen gas, which gas is caused to flash or ignite by an arc occurring at charging terminals upon mounting or dismounting of the battery pack with respect to the charger, the generated gas may happen to accumulate in the battery pack so that, upon being mounted to the machine or the like, the hydrogen gas will invade into machine body to be caused to draw fire by the arc of incorporated motor, switch or the like, and so on. In the case of the nickel-hydrogen battery, in particular, hydrogen is charged in the battery, and the above problems have been apt to readily occur.
In order to eliminate such problem, a Japanese Utility Model Publication No. Hei 5-37634 has disclosed an arrangement in which a battery pack is provided with an aperture, a charger is provided with a blower so that, when the battery pack is mounted to the charger with respect to the aperture, any heated air within the battery pack will be forcibly discharged by a blower.
In Japanese Utility Model Laid-Open Publication No. Hei 5-84023, there has been suggested another arrangement in which a connecting part between the charger and the battery pack is provided with a vent hole for exhausting the hydrogen gas.
In another japanese Utility Model Laid-Open Publication No. Hei 6-54209, there has been disclosed a charger which blasts air with an incorporating blower into a battery pack having holes at mutually opposing positions, cause a ventilation through the interior of the battery pack.
In the first mentioned publication 5-37634, however, there has been a problem that the blower in the charger is positioned remote from the aperture of the battery pack so that air from the blower does not reach efficiently the aperture. Further, a heated air due to heat generation of a transformer or the like in a charging circuit is also blasted by the blower, and the battery cannot be efficiently cooled, as another problem. Further, an air current generated by the blower is directed diagonal in accordance with a slant of vanes as an inherent characteristic of blower fan, so that, the cooling effect for the batteries positioned in the direction of such diagonal air current generated by the blower will be higher but the effect for the batteries not positioned in the particular direction will be lower. For this reason, there arises a further problem that the batteries as a whole cannot be cooled uniformly, the cooling effect of the entire battery pack is lowered, and eventually exhausting effect of hydrogen gas is also lowered. Yet, an exhaust port for interior air inside the battery pack is disposed on a side wall and closer to a vent port leading air current into the pack, so that the air current cannot reach the whole area inside the battery pack, the blasted air of the blower does not reach the respective batteries effectively, due to also the remote position from the aperture of the battery pack as has been referred to, and the discharge effect for the hydrogen gas is also insufficient, in addition to the low cooling effect, as another problem.
In the case of the foregoing publication 5-84023 in which the vent hole is provided at the connecting part between the charger and the battery pack for discharging the hydrogen gas, there has been a risk that it has required a long time until the hydrogen gas is fully discharged and the gas may even be left without being fully discharged.
In the case also of the foregoing publication 654209 where the blower in the charger blasts air into the battery pack through the mutually opposing holes of the pack, the holes are made in laterally opposing walls of the battery pack, the hydrogen gas is caused thereby to stay in upper part of the battery pack without being fully discharged, and even hot air due to the heat generation of the batteries will also stay in the upper part of the battery pack without being discharged, and the cooling effect is deteriorated, to be further problems unsolved. There still has been a risk that, because the battery pack is to be mounted and dismounted with respect to the charger, there has been a gap between the vent ports of the battery pack and the blast ports of the charger, so that the blasted air is caused to leak to the exterior, to lessen the vent air sent to the battery pack and thus the cooling effect is further deteriorated.
An object of the present invention is present invention is to provide a charger capable of overcoming the respective problems in the foregoing related art, blasting a larger amount of air into the battery pack highly efficiently, discharging highly efficiently the hydrogen gas generated by the batteries highly efficiently, and elevating the battery cooling effect and gas discharging effect. Another object is to provide a charger capable of uniformly cooling a plurality of batteries with a simpler structure even when the diagonal air current is caused to enter through the vent ports due to characteristics of vanes of the blower. Still another object is to provide a charger which is capable of allowing the blasted air from the blower to readily reach the entire range in the interior of the battery pack, so as to be able to sufficiently and uniformly cool the respective batteries and to fully discharge the hydrogen gas in a short time.
According to the present invention, the above objects can be realized by means of a charger comprising a battery pack housing therein a plurality of batteries and having a projection provided on outer periphery with a contacting terminal means, first vent ports in a side wall on which the projection is disposed, and second vent ports in an opposite side wall to that of the first vent ports; and a charger section having a mounting hole provided on inner periphery with a charging terminal means for charging the batteries in the battery pack with the projection thereof mounted in the mounting hole, blast ports made at positions opposing the first vent ports of the battery pack as mounted, and a blower for blowing air towards the blast ports, the air thus blown being blast from the blast ports through the first vent ports into the interior of the battery pack. When the battery pack is set onto the charger section with the projection mounted in the mounting hole, therefore, the first vent ports of the battery pack can be opposed to the blast ports of the charger section, so that much air can be blown from the blower through the blast ports and first vent ports into the battery pack, and the plurality of batteries can be efficiently cooled while being charged.
Other objects and advantages of the present invention shall become clear as the description of preferred embodiment of the invention advances as detailed with reference to accompanying drawings showing the embodiment.